Snow bike and a front suspension for a snow bike

ABSTRACT

A front fork assembly of a snow bike is disclosed having left and right legs, each having an upper leg portion and a lower leg portion. The left leg upper and lower leg portions are linearly movable relative to each other. A right leg has an upper leg portion and a lower leg portion, the right leg upper and lower leg portions are linearly movable relative to each other. A ski mount has a lower end for coupling to a ski and an upper end for coupling to the left and right leg. A linear force element is coupled to the left and right legs with a first end adjacent the first ends of the forks and seconds ends coupled to the ski, the linear force element has a different linear force characteristic than the left and right legs.

BACKGROUND

The present disclosure relates to a snow bike and in particular to a front suspension for a snow bike.

Snow bikes are known in the snowmobile art. These vehicles are usually converted for winter use by converting a dirt bike into a snow bike, by replacing the front tire with a ski and the rear wheel with a rear suspension and track. Such snow bikes are known from our US patents and patent applications, namely: U.S. Pat. No. 8,910,738; Publications 2012/0222908; 2015/0144412; 2015/0259032; 2016/0280331 and application Ser. Nos. 14/935,224; 14/935,265 and 15/165,862; the subject matter of which are incorporated herein by reference.

SUMMARY

In one embodiment of the invention, a front fork assembly of a snow bike comprises a left leg having an upper leg portion and a lower leg portion, the left leg upper and lower leg portions being linearly movable relative to each other; a right leg having an upper leg portion and a lower leg portion, the right leg upper and lower leg portions being linearly movable relative to each other; a ski mount having a lower end for coupling to a ski and an upper end for coupling to the left and right leg; and a linear force element coupled to the left and right legs with a first end adjacent the first ends of the forks and seconds ends coupled to the ski, the linear force element having different linear force characteristic than the left and right legs.

In another embodiment, a front fork assembly of a snow bike comprises a left leg having an upper leg portion and a lower leg portion, the left leg upper and lower leg portions being linearly movable relative to each other; a right leg having an upper leg portion and a lower leg portion, the right leg upper and lower leg portions being linearly movable relative to each other; a ski mount having a lower end for coupling to a ski and an upper end for coupling to the left and right leg; and a linear force element coupled to the left and right legs with a first end adjacent the first ends of the forks and seconds ends coupled to the ski, wherein the linear force element is an air shock.

In yet another embodiment, a snow bike comprises a frame; a powertrain supported by the frame; a rear suspension; a drive supported by the rear suspension and coupled to the drivetrain and a front suspension. The front suspension comprises a left leg having an upper leg portion and a lower leg portion, the left leg upper and lower leg portions being linearly movable relative to each other; a right leg having an upper leg portion and a lower leg portion, the right leg upper and lower leg portions being linearly movable relative to each other; a ski mount having a lower end for coupling to a ski and an upper end for coupling to the left and right leg; a linear force element coupled to the left and right legs with a first end adjacent the first ends of the forks and seconds ends coupled to the ski, the linear force element having different linear force characteristic than the left and right legs; and a front ski coupled to the front suspension.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will now be described by way of reference to the drawing figures, where:

FIG. 1 is a left side view of the snow bike and front suspension of the present disclosure;

FIG. 2 is a front left perspective view of the front suspension shown in FIG. 1;

FIG. 3 is a left rear view of the front suspension shown in FIG. 2;

FIG. 4 is a left side view of the suspension of FIG. 2;

FIG. 5 is a perspective view similar to that of FIG. 3 showing the suspension in an exploded manner;

FIG. 5A is an enlarged view of the spindle portion of the ski mount shown in FIG. 5;

FIG. 6 is a cross-sectional view taken through lines 6-6 of FIG. 2;

FIG. 7 is a cross-sectional view taken through lines 7-7 of FIG. 2;

FIG. 8 is a cross-sectional view taken through lines 8-8 of FIG. 2;

FIG. 9 is a view similar to that of FIG. 2 showing the suspension in a fully compressed configuration;

FIG. 10 is a view similar to that of FIG. 3 shown in a fully compressed condition;

FIG. 11 is a view similar to that of FIG. 4 shown in suspension in a fully compressed condition; and

FIG. 12 is a view similar to that of FIG. 3 showing an alternate lower shock mounting.

DETAILED DESCRIPTION

With reference first to FIG. 1, a snow bike is shown generally at 2. Snow bike 2 includes a dirt bike 4 having the front and rear wheels removed. Snow bike 2 includes a frame 6, a powertrain 8, a seat 10, steering assembly 12 including handlebars 14, and a front suspension 15. Front suspension is in part defined by the existing front fork assembly having forks 18, designated as left front fork 18L and right front fork 18R. A front fender 20 is positioned between the front forks 18. As shown, front wheel is removed and replaced with a front ski mount 28 which couple to the forks 18 as discussed herein. The rear wheel is removed and includes a rear suspension 30, including a tunnel 32 and a track 34. Rear suspension 30 could be similar to any of the rear suspensions shown in our US patents and applications, namely: U.S. Pat. No. 8,910,738; Publications 2012/0222908; 2015/0144412; 2015/0259032; 2016/0280331 and application Ser. Nos. 14/935,224; 14/935,265 and 15/165,862; the subject matter of which are incorporated herein by reference.

With reference now to FIGS. 2-4, front suspension 15 is shown comprising the forks or legs 18L and 18R which are coupled to ski mount 28, which in turn is coupled to front ski 40. It should be understood that left leg 18L and right leg 18R are coupled to the frame 6 of the snow bike by way of a triple clamp 42 having a lower left clamp portion 44L and a lower right hand clamp portion 44R; and an upper left clamp portion 46L and an upper right clamp portion 46R. These clamp portions clamp to associated legs 18L and 18R as is known in the art. Triple clamp 42 also includes a center pin 48 which may couple to a down tube (not shown) of the frame 6, such that legs 18L and 18R may rotate about pin 48 for steering. As shown in FIGS. 2-4, lower ends of the legs 18L and 18R are coupled to the ski mount 28 in order to turn the ski 40 for purposes of steering. As also shown, front suspension 15 further includes a linear force element 49 which is coupled between a bottom of triple clamp 42 and a top of the ski mount 28, as further described herein.

With reference now to FIGS. 5-8, the ski mount 28 will be described in greater detail. With reference first to FIG. 5A, ski mount 28 includes a spindle 50 having spaced apart plate portions 52. The plate portions 52 are spaced apart by way of a box-shaped inner plate 54 and a pin 56. A bracket 60 has a base portion 62 coupled between plates 52 and includes a clevis 64 having apertures at 66. Upper ends of plates 52 include apertures at 70 and lower ends of plate 52 include apertures 72.

As shown in FIG. 5, brackets 76 are coupled to a top of the plates 52 by way of fasteners 78 extending through apertures 80 of bracket 76 and into threaded engagement with threaded apertures 70 (FIG. 5A). Brackets 76 retain clamps 86 by way of fasteners 88 and 90 which couple to ends of legs 18L and 18R as best shown in FIG. 2. Brackets 76 could be integrated with plate portions 52 which would extend from an upper edge of the plate portions 52.

A lower coupler 100 is coupled to apertures 72 (FIG. 5A) by way of fasteners 102, 104 and 106. Fasteners 102 extend through apertures 110 of coupler 100. Coupler 100 is also coupled to ski 40 and in particular, to a mount portion 120 of ski 40 where ski mount 120 includes up standing walls 122 having apertures 124. Coupler 100 includes an aperture at 130 which receives a sleeve 132 which thereupon receives bushings 134, thereover. As shown best in FIG. 8, bushings 134 overlap sleeve 132 and sleeves 138 extend into aperture 124 (FIG. 5 of ski mount 120). Spacers 136 extend between heads of the bushings 134, 138. Fastener 140 is received through washer 142 through aperture 124 and through a combination of bushings 138, 136, 134 and sleeve 130 to receive fasteners 150 and 152. Fasteners 140, 150 and 152 couple the ski 40 to the coupler 100. A rubber mount 160 is positioned in the ski mount 120 and conforms to, but allows movement between, coupler 100 and ski 40 as best shown in FIG. 6.

Finally, as shown in FIG. 5, suspension 15 includes bracket 170 having a clevis 172. Bracket 170 is mounted to a bottom of the triple clamp 42 through apertures 174. As shown best in FIG. 7, bracket 170 traps fender 20 between triple clamp 42 and bracket 170. Thus, as shown in FIG. 5, linear force element 49 is coupled to the snow bike 2 by way of fastener 176 extending through aperture 180 of linear force element 49 and through clevis 172; and by way of fastener 182 extending through aperture 178 of linear force element 49 and through clevis 64 (FIG. 5A). Thus, linear force element 49 supplements the existing shocks in the front legs 18L and 18R.

With reference now to FIGS. 9-11, the operation of the front suspension 15 will now be described in greater detail. As shown, suspension 15 is shown in the fully collapsed state where both the shock absorbers of the front forks 18L, 18R and linear force element 49 are shown in a fully compressed state. As shown, linear force element 49 is an air shock available from Fox Shox and has the same linear travel as the motor bike forks 18L, 18R; a range of 8 to 14″, preferably 10 to 12″. In the embodiment shown the linear travel is 11″. In the embodiment shown, linear force element 49 is an EVOL Series Float shock available from Fox Shox located at 915 Disc Dr., Scotts Valley, Calif. 95066. This shock is an air shock with a progressive rate which progressive range is adjustable.

While the LFE 49 is shown herein as an air shock, other linear force elements are possible. For example, the linear force element could be a gas shock or a shock with a spring over, similar to that described in our U.S. Pat. No. 8,079,602. The linear force element could also be a hydraulic shock, or a spring or a series of springs. These components could have a linear or progressive rate which rate is adjustable. In addition, linear force element could be a linkage coupled between the triple clamp and the ski, a linkage similar to that described in our US Patent as the coupled suspension system. In that way, the stroke of the shock could be tuned to vary from the stroke of the front forks 18L and 18R.

Linear force element 49 works in combination with the motor bike shocks within forks 18L, 18R to give the front forks the proper spring rate and damping force for the snow bike. In the embodiment shown, linear force element 49 is also in compression the entire time; that is between the positions shown in 2-4 and 9-11.

It should be appreciated that the spindle 50 could be comprised of an integrated unit where the all of the components are fixed to each other, namely spindle 50, brackets 76, the inner portions of brackets 86 and coupler 100. This could be assembled by such means as welding or adhesives for example. The integrated spindle could also be a forging or casting which is in a homogenous state.

It should also be appreciated that a lower end of the LFE 49 could be attached to a modified coupler 100. As shown in FIG. 12, a coupler 200 is shown at 200, which is identical to coupler 100, yet it includes a notch at 202 to receive a lower end of LFE 49. In this manner, fastener 102 couples both the coupler 200 and the LFE 49, as fastener 102 extends through aperture 178 (FIG. 5) of LFE 49.

In the above described embodiment, the ski mounts 28 and linear force element 49 are designed as a kit for converting a motorbike to a snow bike having existing shocks positioned in the front forks, or for retrofitting existing snow bikes. In the case where a new snow bike front suspension is desired, the front suspension could include front forks 18L and 18R, but in this case, the front forks would not include internal shocks, but rather would only be struts which allow linear telescopic movement but would not have any internal dampening resistance. While this design would include a linear force element 49, the spring rate of the combined suspension 15 would still be consistent with that disclosed above.

While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. 

What is claimed is:
 1. A front fork assembly of a snow bike, comprising: a left leg having an upper leg portion and a lower leg portion, the left leg upper and lower leg portions being linearly movable relative to each other; a right leg having an upper leg portion and a lower leg portion, the right leg upper and lower leg portions being linearly movable relative to each other; a ski mount having a lower end for coupling to a ski and an upper end for coupling to the left and right leg; and a linear force element coupled to the left and right legs with a first end adjacent first ends of the forks and a second end coupled to the ski, the linear force element having different linear force characteristic than the left and right legs, wherein the upper leg portions of the left and right legs are coupled to each other by way of a triple clamp and an upper end of the linear force element is coupled to a bottom of the triple clamp.
 2. The front fork assembly of claim 1, wherein the left and right legs include shock absorbers.
 3. The front fork assembly of claim 2, wherein the linear force element is a shock absorber.
 4. The front fork assembly of claim 3, wherein the linear force element is a gas shock.
 5. The front fork assembly of claim 3, wherein the linear force element is a hydraulic shock.
 6. The front fork assembly of claim 3, wherein the shock absorber has a spring over the shock.
 7. The front fork assembly of claim 3, wherein the linear force element is an air shock.
 8. The front fork assembly of claim 3, wherein the shock absorber has a linear travel in the range 8-14 inches.
 9. The front fork assembly of claim 8, wherein the shock absorber has a linear travel in the range 10-12 inches.
 10. The front fork assembly of claim 3, wherein the shock absorber is always in compression.
 11. The front fork assembly of claim 1, wherein the linear force element has a progressive rate.
 12. The front fork assembly of claim 11, wherein the progressive rate is adjustable.
 13. The front fork assembly of claim 1, wherein the linear force element is attached to a bracket coupled to a bottom of the triple clamp.
 14. The front fork assembly of claim 1, wherein the ski mount comprises a spindle.
 15. The front fork assembly of claim 14, wherein the spindle comprises a bracket and a lower end of the linear force element is coupled to the bracket.
 16. The front fork assembly of claim 14, wherein the spindle comprises a coupler for coupling to a ski, and a lower end of the linear force element is attached to the coupler.
 17. The front fork assembly of claim 1, wherein the left and right legs are struts with linear movement.
 18. A front fork assembly of a snow bike, comprising: a left leg having an upper leg portion and a lower leg portion, the left leg upper and lower leg portions being linearly movable relative to each other; a right leg having an upper leg portion and a lower leg portion, the right leg upper and lower leg portions being linearly movable relative to each other; a ski mount having a lower end for coupling to a ski and an upper end for coupling to the left and right leg; and a linear force element coupled to the left and right legs with a first end adjacent first ends of the forks and a second end coupled to the ski, wherein the linear force element is an air shock, the linear force element providing dampening to the right and left leg during the linear movement of the upper and lower leg portions.
 19. The front fork assembly of claim 18, wherein the left and right legs include shock absorbers.
 20. The front fork assembly of claim 18, wherein the air shock has a progressive rate.
 21. The front fork assembly of claim 20, wherein the progressive rate is adjustable.
 22. The front fork assembly of claim 18, wherein the air shock has a linear travel in the range 8-14 inches.
 23. The front fork assembly of claim 22, wherein the air shock has a linear travel in the range 10-12 inches.
 24. The front fork assembly of claim 18, wherein the air shock is always in compression.
 25. The front fork assembly of claim 18, wherein the upper leg portions of the left and right legs are coupled to each other by way of a triple clamp.
 26. The front fork assembly of claim 25, wherein an upper end of the linear force element is coupled to a bottom of the triple clamp.
 27. The front fork assembly of claim 26, wherein the linear force element is attached to a bracket coupled to a bottom of the triple clamp.
 28. The front fork assembly of claim 18, wherein the ski mount comprises a spindle.
 29. The front fork assembly of claim 28, wherein a lower end of the linear force element is attached to a bracket coupled to the spindle.
 30. The front fork assembly of claim 18, wherein the left and right legs are struts with linear movement.
 31. A snow bike, comprising: a frame; a powertrain supported by the frame; a rear suspension; a drive supported by the rear suspension and coupled to the drivetrain; a front suspension, comprising: a left leg having an upper leg portion and a lower leg portion, the left leg upper and lower leg portions being linearly movable relative to each other; a right leg having an upper leg portion and a lower leg portion, the right leg upper and lower leg portions being linearly movable relative to each other; a ski mount having a lower end for coupling to a ski and an upper end for coupling to the left and right leg; a linear force element coupled to the left and right legs with an upper end adjacent upper ends of the forks and a lower end coupled to the ski, the linear force element having different linear force characteristic than the left and right legs; and a front ski coupled to the front suspension.
 32. The snow bike of claim 31, wherein the left and right legs include shock absorbers.
 33. The front fork assembly of claim 31, wherein the linear force element has a progressive rate.
 34. The front fork assembly of claim 33, wherein the progressive rate is adjustable.
 35. The snow bike of claim 31, wherein the linear force element is a shock absorber.
 36. The snow bike of claim 35, wherein the shock absorber has a linear travel in the range 8-14 inches.
 37. The snow bike of claim 36, wherein the shock absorber has a linear travel in the range 10-12 inches.
 38. The snow bike of claim 35, wherein the shock absorber is an air shock and is always in compression.
 39. The snow bike of claim 31, wherein the upper leg portions of the left and right legs are coupled to each other by way of a triple clamp.
 40. The snow bike of claim 39, wherein an upper end of the linear force element is coupled to a bottom of the triple clamp.
 41. The snow bike of claim 40, wherein a bracket is coupled to the bottom of the triple clamp and the upper end of the linear force element is attached to bracket.
 42. The snow bike of claim 31, wherein the ski mount comprises a spindle.
 43. The snow bike of claim 42, wherein the spindle comprises a bracket and a lower end of the linear force element is coupled to the bracket.
 44. The front fork assembly of claim 42, wherein the spindle comprises a coupler for coupling to a ski, and a lower end of the linear force element is attached to the coupler.
 45. The snow bike of claim 31, wherein the left and right legs are struts with linear movement.
 46. The front fork assembly of claim 31, wherein the linear force element has a progressive rate.
 47. The front fork assembly of claim 46, wherein the progressive rate is adjustable. 